2 Answers

This article gives a good breakdown of the milestones (e.g., we can’t just take 8.5 billion and divide by the number of seconds since they launched, since the rate at which they sold songs is different over time).

The most recent milestone (the last 500 million songs) happened over 50 days, which would be 10 million songs per day, or 416,700 per hour, 6945 per minute, or around 116 songs per second. Note that these are averages—there are times when itunes is selling far more than 116 songs per second.

Notably, in 2004 when they went from 150million to 200million in 63 days, they were only selling 793,000 songs per day (a paltry 9 songs per second).

1 dollar (or 75p) per song – that’s 116 dollars (or 72.09 pounds) a second, 6945 dollars (or 4316.61 pounds) per minute, 416,700 dollars (or 258,996.83 pounds) per hour, and 10 million dollars (or 6.21542669 million pounds) a day. So in 3 minutes, they would earn what some people would earn a year. And that’s in the iTunes store alone.